1. Field of the Invention

This invention relates generally to a patient support system for reducing and preventing the development of decubitus ulcers or bed sores in patients. More specifically, the present invention relates to a patient support system comprising multiple support layers whereby each layer is operable to reduce the lateral and normal pressures and forces which can cause such bed sores on a patient. In particular, the present invention relates to a low-air-loss patient support system including an anti-shear cover layer overlapping a fluid bladder or pouch layer which is positioned in overlying relation or integral to the upper surface of a low-air-loss bed.
2. Background
A major concern for health care providers is the prevention of the development of bed sores in bedridden patients. Such bed sores are a frequent medical complication in patients suffering from trauma that can lead to the deterioration of the patient""s skin and underlying tissue. For example, bum victims are extremely susceptible to both the development of bed sores and continued exasperation of existing wounds. Bed sores are also frequently found to occur at the bony protuberances along a patient""s body. More specifically, when a patient lies supinely against a support surface, most of the patient""s weight is supported by the bony protuberances located along such areas as the hip, the scapula, the spinal area, heels and occipital region of the head. As a result, the normal pressures and forces exerted upon these areas by the patient""s weight compresses the capillaries present within the soft tissue surrounding the patient""s skeletal protuberances. This compressive forces causes a reduction in blood circulation to that soft tissue, which may lead to the development of a bed sore.
Other factors which can lead to the development of bed sores include the following: the lateral shearing forces experienced by the patient""s skin as he or she moves or is moved across the support surface, the normal forces and pressures experienced by a patient""s body resting atop a support surface, an accumulation of moisture between the patient""s skin and the patient support surface, and various other medical and traumatic conditions which enhance the breakdown or degradation of a patient""s skin.
Due to the numerous and complex factors leading to the development of bed sores, current product designs have been limited to addressing only particular factors or subsets of factors associated with bed sore development. For instance, in its attempt to solve the problem of bed sores in bedridden patients, U.S. Pat. No. 5,511,260 discloses a mattress pad comprising a film layer positioned atop a fluid bladder layer supported by foam base layer. Though this particular mattress pad may effectively address the normal forces and pressures experienced by a patient""s body resting atop its support surface, it fails to adequately address the problem of moisture accumulation between the patient and the patient support surface. As discussed above, moisture accumulation is a major factor in the development of bed sores. Likewise, U.S. Pat No. 5,044,029 discloses a low-air-oss bed capable of uniformly distributing the supporting pressure points along the body surface, thereby reducing the normal pressures and forces experienced at the critical bony protuberances. This patient support alone, however, does not adequately address the lateral shear forces experienced by the patient as he or she is moved across the support surface. As illustrated, no single prior art provides protection against the wide range of bed sore causing factors. With this in mind, the present invention was developed.
As disclosed, the present invention represents an improved patient support system over the prior art for the prevention of bed sores in patients. As will be appreciated by those skilled in the art, this invention is specially designed to either reduce or prevent a greater number of bed sore causing factors than previously addressed by the prior art. In particular, the present invention provides numerous advantages to bedridden patients heretofore found only associated with separate and distinctly different patient support systems. These advantages include its ability to adjust the positioning and immobilization of the patient as desired by adjusting the air pressure within individual chambers or zones of chambers, its ability to dramatically reduce undesirable lateral shearing forces between the patient and the support surface, its ability to wick moisture away from the patient""s body, and its ability to further reduce normal pressures and forces at specific locations along the patient""s body.
It is, therefore, an object of the present invention to provide a patient support system comprising an inflatable patient support, a fluid bladder or pouch layer positioned in overlying relation to the upper surface of the inflatable patient support, means for securing the fluid bladder layer to the upper surface of the inflatable patient support, an anti-shear cover layer placed in overlying relation to the upper surface of the fluid bladder layer and inflatable patient support, means for securing the anti-shear cover layer to the fluid bladder layer and/or inflatable patient support, and means for facilitating substantial sliding movement between the top and bottom layers of the anti-shear cover layer thereby reducing the lateral shear forces experienced by a patient supported thereon.
It is a further object of the present invention to provide a fluid bladder layer that can be conveniently secured to an existing inflatable patient support.
Another object of the present invention is to provide a fluid bladder layer in which the fluid bladders or pouches are secured atop an inflatable patient support in configuration that is customized to the pressure points along a particular patient""s body.
Another object of the present invention is to provide a fluid bladder layer assembled with releasable discrete fluid bladders or pouches so as to allow such bladders or pouches to be removed or replaced as may be required.
Another object of the present invention is to provide an inflatable patient support having attachment means for securing at least one fluid bladder or pouch to the upper surface of the inflatable patient support to form a fluid bladder layer.
Another object of the present invention is to provide a patient support system comprising an anti-shear cover layer, a fluid bladder layer, and an inflatable patient support where at least a portion of each is specially designed and fabricated with a gas permeable surface material to enable moisture on the patient""s body to be directed into the air chambers of the inflatable patient support where it is removed by the circulation of fresh inflation air.
Another object of the present invention is to provide an inflatable patient support having at least a portion of which is made of a moisture vapor permeable material.
Another object of the present invention is to provide an anti-shear cover layer comprised of a top layer bounded to a bottom layer to form an internal chamber for containing a lubricant that enhances the relative sliding movement between the adjacent contacting surfaces of the top layer and bottom layer and, thus, allows a patient resting atop the top layer to slide relative to the bottom layer thereby reducing the frictional force normally experienced by a patient moving across a patient support surface.
Another object of the present invention is to provide an anti-shear cover layer that can be quickly and easily removed to allow for convenient maintenance to the underlying fluid bladder layer or inflatable patient support as may be required.
Another object of the present invention is to provide a means for regulating the temperature of the fluid contained within the fluid bladder layer and, thereby, allow the operator or patient to effectively maintain a desired patient body surface temperature.
Other objects and advantages will be apparent to those of ordinary skill in the art from the following disclosure.
These objects and advantages are accomplished in the present invention by providing a patient support system comprising an anti-shear cover layer for overlapping a fluid bladder layer positioned atop an inflatable patient support. The anti-shear cover layer is comprised of a top fabric layer forming a patient support surface and a bottom fabric layer positioned substantially adjacent to the top surface of a fluid bladder support layer. The peripheral edge of the top fabric layer is secured to the peripheral edge of the underlying bottom fabric layer which forms a chamber between the top and bottom layers, into which a lubricant material is disposed to enhance slippage between the contacting surfaces of the two layers. The bottom surface of the bottom layer is secured to the fluid bladder layer by connecting means and/or frictional forces and is, therefore, generally held in a fixed position. The top fabric layer, however, is only secured about its peripheral edge to the bottom fabric layer and is, therefore, able to slide relative to the bottom fabric layer. In this manner, a patient resting atop the anti-shear cover layer experiences reduced frictional and lateral shear forces as the top patient support layer, through the action of the lubricant material, is able to slide relative to the bottom layer which is relatively affixed to the top surface of either the fluid bladder layer or inflatable air mattress. Under certain circumstances and with particular patient supports, it may be desirable to provide means which prevent any excessive slippage of a patient supported on an anti-shear cover layer. For example, the middle section of the top fabric layer, corresponding to the torso section of the patient, can be attached to the bottom fabric layer. In this way, movement of the patient""s torso section is limited; however, the patient""s upper and lower body are able to slide relative to the underlying bottom layer of the anti-shear cover layer. At least a portion of the anti-shear cover layer is constructed of a water vapor permeable material to help eliminate moisture from between the patient""s body and the contacting surface of the top layer.
Also provided is a fluid bladder layer comprising a plurality of discrete fluid bladders or pouches for reducing the normal pressures and forces experienced by a patient resting atop the patient support surface. The fluid bladder layer is specially designed to be positioned in overlying relation to the upper surface of an inflatable patient support, and is provided with means to releasably secure the fluid bladder layer to the inflatable patient support. The fluid bladder layer includes one or more discrete fluid pouches releasably or integrally secured to a fabric sheet at positions on the fabric sheet which correspond to increased pressure points on the patient""s body, such as the heel, buttocks, or scapula. The fluid pouch retaining fabric sheet is draped over the underlying inflatable patient support, thereby arranging the fluid pouches on the upper surface of the inflatable patient support at preferred positions corresponding to areas on the patient""s body which may be susceptible to the development of bed sores. Using individually detachable fluid pouches enables the fluid bladder layer to be customized to best suit the characteristics of a particular bed user. Portions of the fabric sheet are constructed of a water vapor permeable material to promote the elimination of moisture from the patient""s body.
Also provided is a fluid bladder layer comprising a plurality of discrete fluid pouches operably secured to specific positions atop an inflatable patient support More specifically, the fluid bladder layer is formed by securing one or more discrete fluid pouches directly to the surface of the inflatable patient support at positions which correspond to areas on the patient""s body that are susceptible to bed sore development. Alternatively, a fluid bladder layer is provided as an integral component of an inflatable patient support. In this way, the inflatable air chamber or air chambers comprising an inflatable patient support are assembled having fluid pouches integrally secured substantially adjacent to the upper surface of the inflatable patient support.
Also provided is a low-air-loss bed comprising at least one gas permeable air chamber mounted on a base frame, and placed in fluid communication with a source of gas. The air chamber or chambers are in communication with a gas source operable to change the amount of gas delivered to the air chamber or chambers, thereby varying the amount of support provided for each portion of the patient. The air chamber or chambers may be constructed of a first material which is relatively impermeable to gas and a second material which is gas permeable, the sides and bottom of each chamber being preferably constructed of the second material.
Further objects and advantages of the invention will be readily apparent to those skilled in the art from the following description taken in conjunction with the accompanying drawings. The drawings constitute part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.